1. Technical Field
The invention relates to clamping means and more particularly to a clamp assembly adapted to affix a resilient elastomeric sleeve member to a metal wall of a suspension system or to an end cap of an air spring. Specifically, the invention relates to a clamp assembly employing a clamping member having a radially extending convex projection which coacts with a corresponding concave recess wherein the projection has a different radius of curvature than that of the recess so as to provide a pair of pinch areas on opposite sides of the radially aligned centers of the recess and projection, whereby the rubber is squeezed outwardly so the clamping load does not act directly on the member being crimped to prevent it from being crushed.
2. Background Information
Pneumatic springs commonly referred to as air springs, have been used for many applications, including motor vehicles, for a number of years to provide cushioning between movable parts of the vehicle, primarily to absorb shock loads impressed on the vehicle axles by the wheels striking an object in the road or falling into a depression. The air spring usually consists of a flexible elastomeric sleeve or bellows containing a supply of compressible fluid and has one or more pistons movable with respect to the flexible sleeve. The piston causes compression and expansion of the fluid within the sleeve as the sleeve compresses and expands as the vehicle experiences the road shock. The spring sleeve is formed of a flexible elastomeric material containing reinforcing cords, and permits the piston to move axially with respect to another piston or end cap secured within open ends of the sleeve.
The open ends of the elastomeric sleeves are sealingly connected to the piston and/or opposite end cap, and the integrity of this connection is always one of the important and major aspects in producing an efficient and maintenance-free air spring. One problem that can occur with air springs, and in particular, the clamp ring therefor, is that the clamp ring will move in its clamped position under dynamic air spring conditions causing movement of the clamped elastomeric material therebetween tending to loosen the sealing engagement and deteriorating the clamp integrity and causing ultimate air spring leakage and failure. This ring movement is especially critical during the jounce or collapsing stroke.
Another problem that can occur with air springs and the clamping of the elastomeric sleeve ends to the piston member, end cap or other component of a suspension system, is to secure a sufficiently tight seal to enable the air spring to withstand high fluid pressures in the fluid chamber without premature leakage or bursting even upon experiencing severe air spring movement and being exposed to the harsh environments on the undercarriage of a vehicle.
Air springs are also used in combination with other types of suspension systems, such as those incorporating shock absorbers. Examples of such composite suspension systems are shown in U.S. Pat. Nos. 2,149,040 and 3,819,166.
Although these prior art clamping members provide satisfactory fluid-type seals with the end member of the air spring, the seal is usually obtained by applying a large force on the clamping ring to swage it into an extremely tight clamping fit against the air spring end member in order to squeeze and crimp the material of the elastomeric sleeve therebetween. It is difficult to utilize such a clamp ring and current method of crimping where the member with which the clamp ring is utilized is of a thin metal, such as when the open end of the air spring sleeve is crimped to the thin wall body of a composite suspension system utilizing an internal hydraulic or pneumatic shock absorber. The relatively thin wall of the metal member surrounding the internal shock absorber cannot withstand the large crimping force which is usually applied to the clamp ring or clamp member of existing air springs. In these prior clamp assemblies, the force applied against the intervening rubber located between the member being clamped to and the clamping ring, is usually applied uniformly to the rubber sleeve to provide a sufficient gripping force to withstand the internal pressures on the air spring, or the force is concentrated at areas usually located between the apex of a radially extending projection and the aligned bottom of a concave recess.
Therefore, the need exists for an improved clamp assembly for use with air springs, especially when clamping the open end of the elastomeric sleeve against a relatively thin metal member, which does not sacrifice the holding power of the clamp assembly, and which enables the internal pressure in the elastomeric sleeve to be maintained without damaging or distorting the metal member.